How do I know that he hasn't studied post-bop drumming? Because the situation calls for the type of over the bar line syncopated playing that Stan is referencing.

No, you're just saying that it calls for that. Is that a rule, the "over the bar line syncopated" thing? Is everything in jazz drumming played exactly that way and that way only?
Maybe the guy who wrote that song didn't want Phillips to play over the bar line syncopated stuff.
Let's look at it another way. We have the song, the song that Simon Phillips played the drums on, and he played it the way he played. Would any and every "real" jazz drummer play the type of over the bar line syncopation that you're talking about in the way that you mean? Would, say, Ben Riley play it like that, or Shadow Wilson, or Pete La Roca, or Willie Jones? And if they didn't would they also be guilty of not having mastered the "complex jazz ensemble language?"